SpectrophotometricDeterminationofIron(II)andCobalt(II)by...

Hindawi Publishing CorporationInternational Journal of Analytical ChemistryVolume 2012, Article ID 981758, 12 pagesdoi:10.1155/2012/981758

Research Article

Spectrophotometric Determination of Iron(II) and Cobalt(II) byDirect, Derivative, and Simultaneous Methods Using2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone

V. S. Anusuya Devi1 and V. Krishna Reddy2

1 Department of Chemistry, S.E.A. College of Engineering and Technology, Bangalore 560049, India2 Department of Chemistry, Sri Krishnadevaraya University, Anantapur 515003, India

Correspondence should be addressed to V. S. Anusuya Devi, [email protected]

Received 5 September 2011; Revised 24 October 2011; Accepted 3 November 2011

Academic Editor: Ricardo Vessecchi

Copyright © 2012 V. S. A. Devi and V. K. Reddy. This is an open access article distributed under the Creative CommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work isproperly cited.

Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individuallyand simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II)to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximumabsorbance of these complexes was found at 405 nm and 425 nm, respectively. For [Fe(II)-HNAHBH], Beer’s law is obeyed over theconcentration range of 0.055–1.373 μg mL−1 with a detection limit of 0.095 μg mL−1 and molar absorptivity ε, 5.6 × 104 L mol−1

cm−1. [Co(II)-HNAHBH] complex obeys Beer’s law in 0.118–3.534 μg mL−1 range with a detection limit of 0.04 μg mL−1 andmolar absorptivity, ε of 2.3 × 104 L mol−1 cm−1. Highly sensitive and selective first-, second- and third-order derivative methodsare described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method isproposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of variousbiological, water, and alloy samples for the determination of iron and cobalt content.

1. Introduction

Iron and cobalt salts are widely used in industrial materials[1, 2], paint products [3], fertilizers, feeds, and disinfectants.They are important building components in biologicalsystems [4]. Special cobalt-chromium-molybdenum alloysare used for prosthetic parts such as hip and knee replace-ments [5]. Iron-cobalt alloys are used for dental prosthetics[6]. There has been growing concern about the role ofiron and cobalt in biochemical and environmental systems.Normally small amounts of iron and cobalt are essential foroxygen transport and enzymatic activation, respectively, inall mammals. But excessive intake of iron causes siderosis anddamage to organs [7]. A high dosage of cobalt is very toxicto plants and moderately toxic to mammals when injectedintravenously. Hence, quantification of various biologicalsamples for iron and cobalt is very important to know theirinfluence on these systems.

A good number of reviews have been made on the use oflarge number of chromogenic reagents for the spectrophoto-metric determination of iron and cobalt. Some of the recentlyproposed spectrophotometric methods for the determina-tion of iron [8–15] and cobalt [16–22] are less sensitive andless selective. We are now proposing simple, sensitive andselective direct and derivative spectrophotometric methodsfor the determination of iron(II) and cobalt(II) in variouscomplex materials using 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone as chromogenic agent. We are alsoreporting a highly selective second-order derivative methodfor the simultaneous determination of iron and cobalt indifferent samples.

2. Experimental

2.1. Preparation of Reagents. 0.01 M iron(II) and cobalt(II)solutions were prepared by dissolving appropriate amounts

2 International Journal of Analytical Chemistry

OH

CH O NH C

O

OH

2-hydroxy-1-naphthaldehyde

Parahydroxybenzoichydrazide

Reflux

CH N NH C OH

O

2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone

H2N

−H2O

Scheme 1

of ferrous ammonium sulphate (Sd. Fine) in 2 M sulphuricacid and cobaltous nitrate (Qualigens) in 100 mL distilledwater. The stock solutions were diluted appropriately asrequired. Other metal ion solutions were prepared fromtheir nitrates or chlorides in distilled water. 1% solutionof cetyltrimethylammonium bromide (CTAB), a cationicsurfactant in distilled water is used. Buffer solutions ofpH 1–10 are prepared using appropriate mixtures of 1 MHCl–1 M CH3COONa (pH 1–3.0), 0.2 M CH3COOH, 0.2 MCH3COONa (pH 3.5–7.0), and 1 M NH4OH and 1 M NH4Cl(pH 7.5–10.0). HNAHBH was prepared by mixing equalamounts of 2-hydroxy-1-naphthaldehyde in methanol andp-hydroxybenzoichydrazide in hot aqueous ethanol in equalamounts and refluxing for three hours on water bath. Areddish brown coloured solid was obtained on cooling.The product was filtered and dried. It was recrystallizedfrom aqueous ethanol in the presence of norit. The productshowed melting point 272–274◦C.

The structure of the synthesized HNAHBH was deter-mined from infrared and NMR spectral analysis. 1× 10−2 Msolution of the reagent was prepared by dissolving 0.306 gin 100 mL of dimethylformamide (DMF). Working solutionswere prepared by diluting the stock solution with DMF (seeScheme 1).

2.2. Preparation of Sample Solutions

2.2.1. Soil Samples. The soil sample (5.0 g) was weighedinto a 250 mL Teflon high-pressure microwave acid digestionbomb and 50 mL aquaregia were added. The bomb wassealed tightly and then positioned in the carousel of amicrowave oven. The system was operated at full powerfor 30 minutes. The digested material was evaporated toincipient dryness. Then, 50 mL of 5% hydrochloric acid wasadded and heated close to boiling to leach the residue. Aftercooling, the residue was filtered and washed two times witha small volume of 5% hydrochloric acid. The filtrates werequantitatively collected in a 250 mL volumetric flask anddiluted to the mark with distilled water.

2.2.2. Alloy Steel Sample Solution. A 0.1–0.5 g of the alloysample was dissolved in a mixture of 2 mL HCl and 10 mL

HNO3. The resulting solution was evaporated to a smallvolume. To this, 5 mL of 1 : 1 H2O and H2SO4 mixture wasadded and evaporated to dryness. The residue was dissolvedin 15 mL of distilled water and filtered through Whatmanfilter paper no. 40. The filtrate was collected in a 100 mLvolumetric flask and made upto the mark with distilledwater. The solution was further diluted as required.

2.2.3. Food and Biological Samples. A wet ash method wasemployed in the preparation of the sample solution. 0.5 gof the sample was dissolved in a 1 : 1 mixture of nitric acidand perchloric acid. The solution was evaporated to dryness,and the residue was ashed at 300◦C. The ash was dissolved in2 mL of 1 M sulphuric acid and made up to the volume in a25 mL standard flask with distilled water.

2.2.4. Blood and Urine Samples. Blood and urine samplesof the normal adult and patient (male) were collected fromGovernment General Hospital, Kurnool, India. 50 mL ofsample was taken into 100 mL Kjeldal flask. 5 mL con-centrated HNO3 was added and gently heated. When theinitial brief reaction was over, the solution was removed andcooled. 1 mL con. H2SO4 and 1 mL of 70% HClO4 wereadded. The solution was again heated to dense white fumes,repeating HNO3 addition. The heating was continued for30 minutes and then cooled. The contents were filtered andneutralized with dil. NH4OH in the presence of 1-2 mL of0.01% tartrate solution. The solution was transferred intoa 10 mL volumetric flask and diluted to the volume withdistilled water.

2.2.5. Water Samples. Different water samples were collectedfrom different parts of Anantapur district, A. P, India andfiltered using Whatman filter paper.

2.2.6. Pharmaceutical Samples. A known quantity of thesample was taken in a beaker and dissolved in minimumvolume of alcohol. Then added 3 mL of 0.01 M nitric acidand evaporated to dryness. The dried mass was againdissolved in alcohol. This was filtered through Whatmanfilter paper, and the filtrate was diluted to 100 mL with

International Journal of Analytical Chemistry 3

Table 1: Tolerance limits of foreign ions, Amount of Fe(II) taken = 0.558 μg mL−1 pH = 5.0.

Foreign ionTolerance limit

(μg mL−1)Foreign ion

Tolerance limit(μg mL−1)

Foreign ionTolerance limit

(μg mL−1)

Sulphate 1440 Na(I) 1565 La(III) 18

Iodide 1303 Mg(II) 1460 Ag(I) 15

Phosphate 1424 Ca(II) 1440 Hg(II) 16

Thiosulphate 1424 K(I) 1300 U(VI) 6,60a

Tartrate 1414 Ba(II) 1260 Mn(II) 4,55a

Thiourea 1140 Pd(II) 63 Th(IV) 3,50a

Bromide 1138 Cd(II) 45 In(III) 4,60a

Nitrate 930 Bi(III) 42 Sn(II) <1,50a

Carbonate 900 W(VI) 37 Co(II) <1,55a

Thiocyanate 870 Hf(IV) 36 Ni(II) <1,60b

Chloride 531 Ce(IV) 28 Zn(II) <1,80b

Fluoride 285 Cr(VI) 27 Al(III) <1,45a

EDTA 124 Mo(VI) 22 Cu(II) <1,50a

Citrate 115 Zr(IV) 19

Oxalate 95 Sr(II) 18

In the presence of a = 500μg of tartrate, b = 400μg of thiocyanate.

Table 2: Determination of iron in surface soil.

Sample Source of the sampleAmount of iron

(mg Kg−1) ± SD∗

S1Groundnut cultivation soilAkuthotapalli, Anantapur

40.98 ± 0.45

S2Cotton cultivation soil,

Singanamala, Anantapur district,27.48 ± 0.36

S3Sweet lemon cultivation soil,

Garladinne, Anantapur distrcct44.88 ± 0.24

S4Paddycultivation soil

Garladinne, Anantapur district20.86 ± 0.37

∗Average of five determinations.

distilled water. The lower concentrations were prepared bythe appropriate dilution of the stock solution.

2.3. Apparatus. A Perkin Elmer (LAMBDA25) spectropho-tometer controlled by a computer and equipped with a1 cm path length quartz cell was used for UV-Vis spectraacquisition. Spectra were acquired between 350–600 nm(1 nm resolution). ELICO model LI-120 pH-meter furnishedwith a combined glass electrode was used to measure pH ofbuffer solutions.

3. Results and Discussions

Iron(II) and cobalt(II) react with HNAHBH forming reddishbrown and yellow coloured complexes. The colour of thecomplexes was stable for more than two days.

3.1. Direct Method of Determination of Iron(II). The absorp-tion spectrum of [Fe(II)-HNAHBH] shows maximum

absorbance at 405 nm. The preliminary investigations indi-cate that the absorbance of the complex is maximum andstable in pH range of 4.5–5.5. Hence pH 5.0 was chosenfor further studies. A considerable increase in the colourintensity in the presence of 0.1% CTAB was observed.Studies on reagent (HNAHBH) concentration effect revealedthat a maximum of 15-fold excess reagent is requiredto get maximum and stable absorbance for the complex.From the absorption spectra of [Fe(II)-HNAHBH] themolar absorptivity, coefficient ε is calculated as 5.6 ×104 L mol−1 cm−1. Variable amounts of Fe(II) were treatedwith suitable amounts of reagent, surfactant, and buffer andthe validity of Beer’s law was tested by plotting the mea-sured absorbance values of the prepared solutions againstconcentration of Fe(II). The calibration curve was linearover the range 0.055–1.373 μg mL−1. The composition of thecomplex [Fe(II) : HNAHBH] was determined as 2 : 3 by Job’scontinuous variation method and the stability constant of thecomplex was calculated as 1.8× 1018. Other analytical resultsare presented in Table 5.

3.1.1. Effect of Diverse Ions in the Determination of Ironby Direct Method. Numerous cations and anions wereadded individually to the experimental solution containing0.558 μg mL−1 of iron and the influence was examined(Table 1). All the anions and many cations were tolerablein more than 100 fold excess. The tolerance limits of someions were in the range of 5–50 folds. Some of the metal ions,which strongly interfered, could be masked using appropriatemasking agents.

3.1.2. Determination of Iron in Surface Soil and Alloy Steelsby Direct Spectrophotometric Method. The applicability ofthe developed direct method was evaluated by applying the


Table 3: Determination of iron in alloy steels.

Alloy steel composition (%)Amount of iron (%)

Certified valuePresent

method± SD∗Relative

error (%)

High tensile steelBY0110-1(42.98 Zn, 19.89 Si, 0.351 Pb, 0.06 Sn, 0.04 Cd, 0.024 As, 0.14 Cu, and4.13 Fe)YSBC19716

4.13 4.06± 0.021 0.17

(34.26 Zn, 0.38 Si, 1.2 Cd, 48.57 Sb, 0.95 S, and 0.32 F)GSBD33001-94

34.26 4.18± 0.022 0.01

(9.29 Al, 1.04 Ca, 9.53 Fe) 9.53 9.46± 0.039 0.08∗

Average of five determinations.

Table 4: Tolerance limits of some cations in derivative methods.

Foreign ionTolerance limit (in folds)

Directmethod

Firstderivative

Secondderivative

Thirdderivative

Ag(I) 14 18 35 22

Hg(II) 11 20 40 30

U(VI) 11 12 25 18

Mn(II) 7 20 16 20

Th(IV) 5 10 16 20

In(III) 7 28 48 34

Au(III) 4 35 55 28

Sn(II) <1 8 15 22

Co(II) <1 interfere 7 15

Ni(II) <1 interfere 5 10

Cu(II) <1 5 12 10

method for the analysis of some surface soil and alloy steelsamples for their iron content. Different aliquots of samplesolutions containing suitable amounts of iron were treatedwith known and required volume of HNAHBH at pH 5.0and 0.1% CTAB and diluted to 10 mL with distilled water.The absorbance of the resultant solutions was measuredat 405 nm, and the amount of iron present was computedfrom the predetermined calibration plot. The results werecompared with the certified values and presented in Tables2 and 3.

3.2. Determination of Iron(II) by Derivative Method. Differ-ent amounts of Fe(II) (0.027–1.375 μg mL−1) were treatedwith suitable amounts of HNAHBH in buffer solutions ofpH 5.0 along with 0.1% CTAB and made upto 10 mL withdistilled water. 1st, 2nd, and 3rd order derivative spectrawere recorded in the wavelength region 350–600 nm. Thefirst-order derivative spectra showed maximum derivativeamplitude at 427 nm (Figure 1). The second-order derivativespectra gave one large trough at 421 nm and a large crust at435 nm with zero cross at 428 nm (Figure 2). A large crustat 415 nm and a large trough at 426 nm with zero crossat 421 nm were observed for the third-derivative spectra

(Figure 3). Hence Fe(II) was determined by measuring thederivative amplitudes at 427 nm for 1st order, at 421 nm and435 nm for 2nd order, and at 415 nm and 426 nm for 3rdorder spectra.

3.2.1. Determination of Iron(II). The derivative amplitudesmeasured at the analytical wavelengths as mentioned abovefor different derivative spectra were plotted against theamount of Fe(II). The calibration plots are linear in the range0.027–1.375 μg mL−1. All the derivative methods are found tobe more sensitive with a wider Beer’s law range than the zeroorder method (Table 5)

3.2.2. Effect of Foreign Ions in Derivative Method of Determi-nation of Iron. The influence of some of the cations, whichshowed serious interference in zero order method, on thederivative amplitudes was studied by the reported methodsand the results obtained are shown in Table 4. It can beobserved from the table that large number of ions showedsignificantly high-tolerance limits in some of the derivativemethods.

3.2.3. Determination of Iron in Food and Biological Samplesby First Order Derivative Method. Known aliquots of theprepared food and biological sample solutions were treatedwith suitable volumes of HNAHBH, buffer solution, andCTAB surfactant and diluted to the volume in 10 mLvolumetric flasks. The first-order derivative spectra wererecorded, and the derivative amplitudes were measured atanalytical wave lengths. The amounts of Fe(II) in the sampleswere computed from predetermined calibration plots andpresented in Table 6. The food and biological samples werefurther analyzed by Atomic Absorbance Spectrophotometricmethod, and the results obtained were compared with thoseof the present method.

3.3. Direct Method of Determination of Cobalt(II). [Co(II)-HNAHBH] complex shows maximum absorbance at425 nm. Maximum and stable absorbance of the complexis achieved in the pH range of 5.0–7.0. Hence pH 6.0was chosen for further studies. A marginal increase inthe absorbance was observed in presence of 0.15% of


Table 5: Analytical characteristics of [Fe(II)-HNAHBH].

ParameterDirect method First derivative Second derivative Third derivative

405 nm 427 nm 421 nm 435 nm 415 nm 426 nm

Beer’s law range(μg mL−1)

0.055–1.373 0.027–1.376 0.027–1.376 0.027–1.376 0.027–1.376 0.027–1.376

Molar absorptivity,(L mol−1 cm−1)

5.6× 104 — — —

Sandell’s sensitivity,(μg cm−2)

0.0012 — — —

Angular coefficient (m) 0.974 0.072 0.006 0.093 0.002 0.085

Y-intercept (b) 0.0047 −0.0045 −0.1× 10−3 −0.1× 10−3 0.2× 10−4 0.9× 10−3

Correlation coefficient 0.9997 0.9999 0.9999 0.9999 0.9999 0.9999

RSD (%) 2.19 0.85 0.76 0.89 1.31 1

Detection limit(μg mL−1)

0.065 0.1 0.022 0.0268 0.036 0.304

Determination limit,(μg mL−1)

0.197 0.3 0.068 0.8 0.11 0.914

Composition (M : L) 2 : 3 — — —

Stability constant 1.8× 1018 — — —

Table 6: Determination of iron in food and biological samples.

Samples

Amount of iron(μg mL−1) ± SD (n = 4)

Found Recovered

present AAS Added present AAS recovery

Wheat 6.68± 0.18 6.40± 0.09 5 11.40± 1.15 11.28± 0.10 97.6

Rice 14.10± 40.25 16.46± 0.18 5 19.7± 40.27 21.04± 0.48 102

Tomato 11.96± 1.20 12.68± 0.14 5 17.68± 0.25 17.44± 0.95 104

Orange 18.12± 0.73 16.94± 0.66 5 22.20± 0.75 22.26± 0.68 96

Banana 10.12± 1.46 11.4± 0.12 5 14.86± 1.45 15.86± 1.46 98.3

Prostate gland 3.26± 0.28 2.98± 0.08 6.5 10.04± 1.68 9.54± 0.94 103

Benign (enlarged prostate gland 12.38± 3.18 13.15± 1.18 6.5 17.96± 1.56 20.18± 1.66 95.12

Table 7: Tolerance limits of foreign ions, amount of Co(II) taken = 1.767 μg mL−1, pH = 6.0.

Foreign ion Tolerance limit (μg mL−1) Foreign ion Tole limit (μg mL−1) Foreign ion Toler limit (μg mL−1)

Tartrate 1707 Na(I) 1666 Au(III) 20

Phosphate 1425 Mg(II) 1530 Sr(II) 18

Sulphate 1440 Ca(II) 1426 Mo(VI) 15

Oxalate 1320 K(I) 1200 Tl(IV) 13

Bromide 1198 Ba(II) 1162 Pd(II) 11,100c

Thiourea 1140 Hf(IV) 72 Th(IV) 6,60a

Thiosulphate 1120 Se(IV) 64 U(VI) 5,60a

Nitrate 930 Cd(II) 56 Mn(II) 5,50a

Chloride 525 W(VI) 55 Cu(II) 2,50a

Carbonate 300 Zr(IV) 46 Ni(II) <1,80b

Fluoride 285 Pb(II) 42 Zn(II) <1

EDTA 144 Hg(II) 40 Sn(II) <1

Citrate 115 Cr(VI) 26 In(III) <1,60a

Bi(III) 21 Ga(III) <1,50a

Ru(III) 21 V(V) <1,50b

In the presence of a = 700μg of tartrate, b = 400μg of oxalate and c = 500μg of thiourea.


Table 8: Determination of cobalt in surface soil samples.

Sample and source Cobalt (μg mL−1)

Presentmethod∗

Reference method[23]

S1Agricultural land(red soil Anantapur.)

16.48± 0.030 17.20± 0.024

S2Agricultural land(black soil, Tadipatri.)

24.15± 0.026 23.68± 0.022

S3Riverbed soil(Tungabhadra river,Kurnool)

14.68± 0.034 15.26± 0.018

S4Industrial soil(electroplatingindustry, Anantapur)

118.40±0.042 122.12± 0.029

∗Average of four determinations.

Table 9: Analysis of blood and urine samples for cobalt content.

Sample source SampleCobalt (μg mL−1)

Presentmethod± SD

(n = 5)

AAS method± SD(n = 5)

Normal adult(male)

Blood 2.44± 0.020 2.48± 0.014

Urine 0.38± 0.010 0.35± 0.022

Anemia patient(female)

Blood 0.86± 0.020 0.92± 0.020

Urine 0.24± 0.030 0.23± 0.014

Paralysis patientBlood 8.46± 0.030 8.65± 0.032

Urine 2.65± 0.020 2.43± 0.025

Pulmonary patientBlood 4.32± 0.015 4.26± 0.010

Urine 1.96± 0.022 2.04± 0.018

Table 10: Tolerance limit of foreign ions (μg mL−1).

Diverse ion Zero order Second derivative Third derivative

Th(IV) 6 55 35

U(VI) 5 40 45

Mn(II) 5 60 20

Cu(II) 2 80 45

Ni(II) <1 30 50

Zn(II) <1 45 20

Sn(II) <1 25 18

In(III) <1 15 28

Ga(III) <1 20 35

V(V) <1 15 20

CTAB. 10-folds excess of HNAHBH is sufficient to getmaximum absorbance. Molar absorptivity of the complexwas calculated as 2.3 × 104 L mol−1 cm−1. Beer’s law istested taking the different amounts of Co(II) in presenceof suitable buffer, surfactant, and HNAHBH, linearity ofthe calibration curve is found between 0.118–3.534 μg mL−1

with a detection limit of 0.04 μg mL−1 and determinationlimit 0.124 μg mL−1 (Table 11), which shows the sensitivityof the present method. The stoichiometry of the complex

410 420 430 440 450 460 470

0

0.015

0.03

0.045

0.06

0.075f

e

d

cba

Wavelength (nm)

−0.015

dA/dλ

Figure 1: First-order derivative spectra of [Fe(II)-HNAHBH].Amount of Fe(II) μg mL−1: a = 0.027; b = 0.055; c = 0.11; d =0.22; e = 0.33; f = 0.88.

420 430 440 450 460 470

0

2

4

f

e

dcb

a

Wavelength (nm)

×10−3

−2

−4

−6

−8

d2A/dλ

2

Figure 2: Second-order derivative spectra of [Fe(II)-HNAHBH].Amount of Fe(II) μg mL−1: a = 0.027; b = 0.055; c = 0.11; d =0.22; e = 0.33; f = 0.88.

was found to be 2 : 3 (Metal : Ligand) by Job’s method. Thestability constant is calculated as 7.7× 1019.

3.3.1. Effect of Foreign Ions in the Determination of Cobaltby Direct Method. The effect of various anions and cationsnormally associated with Co(II) on the absorbance of theexperimental solution was studied. The tolerance limits ofthe tested foreign ions, which bring about a change in theabsorbance by±2% were calculated and presented in Table 7.

Among anions, except EDTA and citrate, all other testedions were tolerable in more than 200-fold excess. EDTAand citrate were tolerable in 144- and 150-fold excess,respectively. Of the tested cations, some of them did notinterfere even when present in more than 500 fold excess,many cations were tolerable between 10–80-folds. Cationswhich interfere seriously are masked with suitable anions.


Table 11: Analytical characteristics of [Co(II)-HNAHBH].

ParameterDirect method Second derivative Third derivative

425 nm 431 nm 443 nm 437 nm 449 nm

Beer’s law range (μg mL−1) 0.118–3.534 0.059–4.712 0.059–4.712 0.059–1.380 0.056–1.380

Molar absorptivity, (L mol−1 cm−1) 2.3× 104 — — — —

Sandell’s sensitivity, μg cm−2 0.003 — — — —

Angular coefficient (m) 0.375 0.0003 0.093 0.0002 0.009

Y-intercept (b) 0.0197 3.2× 10−5 −0.9× 10−4 −0.2× 10−4 −0.9× 10−4

Correlation coefficient 0.9999 0.999 0.9999 0.9999 0.9999

RSD (%) 1.37 1.84 4.3 1.15 7.6

Detection limit (μg mL−1) 0.04 0.06 0.13 0.04 0.21

Determination limit, (μg mL−1) 0.124 0.18 0.39 0.114 0.65

Composition (M : L) 2 : 3 — — —

Stability constant 7.7× 1019 — — —

Table 12: Determination of cobalt in environmental water samples.

Samplecobalt (μg mL−1)

Added FoundRecovery

(%)RSD(%)

Tap water (municipality watersupply, Anantapur)

0.0 0.32 — 2.5

1.5 1.80 98.90 1.8

3.0 3.35 100.90 3.0

4.5 4.83 100.20 2.2

River water (Penna,Tadipatri.)

0.0 1.52 — 3.0

1.5 3.00 99.34 1.6

3.0 4.55 100.66 2.8

4.5 5.95 98.84 4.0

Drain water (vanaspatiindustry, Tadipatri.

0.0 3.60 — 1.7

1.5 5.31 104.12 3.2

3.0 6.48 98.18 2.5

4.5 8.07 99.63 3.6

Table 13: Determination of cobalt in pharmaceutical tablets.

Sample (mg/tablet) Amount of cobalt (μg mL−1)

Reported Found∗Relative

error (%)

Neurobion forte(cyanocobalamine-15 mg)

7.45 7.4 −0.67

Basiton forte(cyanocobalamine-15 mg)

7.42 7.24 −2.42

∗Average of four determinations.

3.3.2. Determination of Cobalt in Surface Soil, Blood andUrine Samples by Direct Method. Suitable aliquots of the soil,blood, and urine sample solutions were taken and analyzedfor cobalt content by the proposed method, and the resultsare presented in Tables 8 and 9. The soil solutions werefurther analyzed by a reference method [23], and biological

410 420 430 440 450

0

5

10

f

e

dcba

Wavelength (nm)

×10−4

−5

−10

−15

d3A/dλ3

Figure 3: Third-order derivative spectra of [Fe(II)-HNAHBH].Amount of Fe(II) μg mL-1: a = 0.027; b = 0.055; c = 0.11; d =0.22; e = 0.33; f = 0.88.

samples were analyzed by flame atomic absorption spec-trophotometer, and the results obtained were compared withthose of present method, which indicate the acceptability ofthe present method.

3.4. Determination of Cobalt by Derivative Method. Variableamounts (0.059–4.712 μg mL−1) of Co(II), taken in different10 mL volumetric flasks, were treated with optimal amountsof reagent HNAHBH at pH 6.0 in presence of 0.15%CTAB, and the derivative spectra were recorded in thewavelength region 350–600 nm against reagent blank. Thesecond-derivative curves (Figure 4) gave a trough at 431 nmand a crust at 443 nm with a zero cross at 437 nm. In thethird-derivative spectra (Figure 5), maximum amplitude wasobserved at 424 nm, 437 nm, 449 nm, and at 462 nm withzero crossings at 431 nm, 443 nm, and 456 nm.


Table 14: Linear regression analysis of the determination of Fe(II) and Co(II) in mixture by second derivative spectrophotometry.

Metal ion determinedWave length (nm)

Other metal present (μg mL−1)Slope Intercept Correlation coefficient

Fe(II) Co(II)

Fe(II) 436 3.9× 10−3 2.4× 10−4 0.9994

0.589 3.2× 10−3 1.9× 10−4 0.9995

Co(II) 426 1.4× 10−4 2.3× 10−6 0.9999

0.33 1.4× 10−4 2.0× 10−6 0.9998

Table 15: Simultaneous second-order derivative spectrophotometric determination of Fe(II) and Co(II).

Amount taken (μg mL−1) Amount found∗ (μg mL−1) Relative error (%)

Fe(II) Co(II) Fe(II) Co(II) Fe(II) Co(II)

0.06 0.59 0.053 (96.3) 0.572 (98.8) −3.6 −2.8

0.12 0.59 0.120 (103.4) 0.592 (100.5) 3.44 0.5

0.23 0.59 0.230 (99.1) 0.586 (99.4) −0.86 −0.5

0.33 0.59 0.334 (101.2) 0.572 (98.8) 1.21 −2.8

0.44 0.59 0.441 (100.2) 0.590 (100.1) 0.22 0.2

0.55 0.59 0.542 (98.5) 0.586 (99.3) −1.45 −0.5

0.33 0.59 0.328 (99.3) 1.120 (94.9) −0.60 −0.7

0.33 1.18 0.326 (89.6) 2.280 (96.6) −1.21 −5.0

0.33 2.36 0.324 (98.1) 3.600 (101.7) −1.81 −3.3

0.33 3.54 0.336 (101.8) 4.670 (98.9) 1.81 1.6

0.33 4.72 0.332 (100.6) 4.670 (98.9) 0.60 −1.0∗Average of four determinations.

3.4.1. Determination of Cobalt. The derivative amplitudesmeasured for different concentrations of Co(II) at appropri-ate wavelengths for 2nd and 3rd order derivative spectra wereplotted against the amount of Co(II) which gave linear plotsin the specified concentration regions. All the parameters likedetection limit, correlation coefficient, and relative standarddeviation values are presented in Table 11.

3.4.2. Effect of Foreign Ions. The selectivity of the derivativemethods was evaluated by studying the effect of metal ionsclosely associated with cobalt on its derivative amplitudesunder experimental conditions. The results are presented inTable 10. The results show that the tolerance limits of Th(IV),U(VI), Mn(II), Cu(II), Ni(II), Zn(II), Sn(II), In(II), Ga(III)and V(V) which interfere seriously in zero order methodwere greatly enhanced in the derivative methods indicatingthe greater selectivity of derivative methods over the directmethod.

3.4.3. Determination of Cobalt in Water and Pharmaceu-tical Samples by Second-Order Derivative Method. Suitablealiquots of water and pharmaceutical samples were takenand analysed for cobalt by second-order derivative method.The results obtained in the analysis of water samples by theproposed method are presented in Table 12 and the validityof the results was evaluated by adding known amounts ofCo(II) and calculating their recovery percentage. The results

410 420 430 440 450 460 470 480

0

4

8

12

16 d

c

b

a

Wavelength (nm)

×10−5

−4

−8

−12

−16

−20

d2A/dλ2

Figure 4: Second-order derivative spectra of [Co(II)-HNAHBH].Amount of Co(II) μg mL−1: a = 0.059, b = 0.118, c = 0.236, and d =0.354.

obtained with pharmaceutical samples were compared withthose obtained by AAS method and presented in Table 13.

3.5. Simultaneous Second-Order Derivative Spectrophoto-metric Determination of Iron(II) and Cobalt(II). Iron and


Table 16: Determination of iron and cobalt in alloy samples.

Sample (composition) Amount (%) Relative error (%)

Certified Found (n = 3) ± SD

Fe(II) Co(II) Fe(II) Co(II) Fe(II) Co(II)

Elgiloy-M(20 Cr; 15 Ni; 0.15 C; 2 Mn; 7 Mo;.05 Be)

15 40 14.82± 0.15 39.39± 0.20 1.33 1.52

Rim alloy(17 Mo; 3Mn)

68 12 69.28± 0.86 12.08± 0.38 1.88 0.66

Sofcomag 25(Fe and Co)

75 25 73.89± 1.38 25.98± 0.86 1.48 3.92

Sofcomag 49(Fe and Co)

51 49 52.12± 0.35 49.18± 0.06 2.18 0.36

410 420 430 440 450 460 470 480

0

1

2

3

4c

b

a

Wavelength (nm)

×10−5

−1

−2

−3

−4

d3A/dλ3

Figure 5: Third-order derivative spectra of [Co(II)-HNAHBH].Amount of Co(II) μg mL−1: a = 0.059, b = 0.118, c = 0.236, andd = 0.354.

cobalt occur together in many real samples like alloysteels, biological fluids, and environmental samples. In mostcases, the characterizations of these samples include thedetermination of their metal ion content. The need forthe determination of iron and cobalt in environmental andbiochemical materials has increased after reports on differentroles of these metals in human health and diseases. We arenow reporting a simple, sensitive, and selective second-orderderivative spectrophotometric method for the simultaneousdetermination of Fe(II) and Co(II) using HNAHBH withoutthe need to solve the simultaneous equations.

3.5.1. Derivative Spectra . The 2nd order derivative spectrarecorded for [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] atpH 5.5 showed sufficiently large derivative amplitude forcobalt at 426 nm while the Fe(II) species exhibit zero ampli-tude (Figure 6). At 436 nm, maximum derivative amplitudewas noticed for Fe(II) where there was no amplitude forCo(II). This facilitates the determination of Fe(II) andCo(II) simultaneously by measuring the second-derivative

410 415 420 425 430 435 440 445 450 455

0

4

8

12

b

a

Wavelength

a = Fe(II)b = Co(II)

−4

−8

−12

−16

d2A/dλ2

×10−4

Figure 6: Second-order derivative spectra of (a) [Fe(II)-HNAHBH]and (b) [Co(II)-NAHBH]. Amount of Fe(II) (μg mL−1): 0.055, 0.11;Co(II) (μg mL−1): 3.53; 4.719.

amplitudes of binary mixtures containing Fe(II) and Co(II)at436 nm and 426 nm, respectively.

3.5.2. Determination of Fe(II) and Co(II). Aliquots of solu-tions containing 0.055–1.650 μg mL−1 of Fe(II) or 0.117–4.719 μg mL−1 of Co(II) were transferred into a series of10 mL calibrated volumetric flasks. HNAHBH (1 × 10−2 M,0.3 mL), CTAB (1%, 1.5 mL), and buffer solution (pH 5.5,4 mL) were added to each of these flasks and diluted tothe mark with distilled water. The zero-crossing pointsof [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] species weredetermined by recording the second-order derivative spectraof both the systems with reference to the reagent blank.Calibration plots for the determination of Fe(II) and Co(II)were constructed by measuring the second-derivative ampli-tudes at zero crossing points of [Co(II)-HNAHBH] (436 nm)and [Fe(II)-HNAHBH] (426 nm), respectively, and plotting


Ta

ble

17:C

ompa

risi

onof

the

resu

lts

wit

hal

read

yre

port

edm

eth

ods.

Met

alio

nR

eage

nt

λ max

(nm

)pH

/med

ium

Aqu

eou

s/ex

trac

tion

Bee

r’s

law

μg

mL−

1ε×

104L

mol−1

cm−1

Inte

rfer

ence

Ref

eren

ce

Fe(I

I)T

hio

cyan

ate-

phen

anth

rolin

e52

0—

Aqu

eou

s0–

241.

87—

[10]

Fe(I

I)2-

[2-(

3,5-

Dib

rom

opyr

idyl

-azo

]-5-

dim

ethy

lam

ino-

ben

zoic

acid

615

2.0–

7.0

Ext

ract

ion

0–5.

59.

36T

l(I)

,Zn

(II)

,Cr(

III)

,W(V

I),

Co(

II),

Cu

(II)

,Ni(

II),

and

Pd(

II)

[24]

Fe(I

I)1,

10-P

hen

anth

rolin

ean

dpi

crat

e51

02.

0–9.

0E

xtra

ctio

n0.

1–3.

613

ED

TA,C

N−

[25]

Fe(I

I)4-

(2-P

yrid

ylaz

o)re

sorc

inol

505

6.0–

7.5

Ext

ract

ion

0–2.

06

Ni(

II),

Co(

II),

Pb(

II),

and

ED

TA[2

6]

Fe(I

I)1,

10-P

hen

anth

rolin

e-te

trap

hen

ylbo

rate

515

4.25

Aqu

eou

s2.

24–3

7.29

1.2

—[2

7]

Fe(I

I)1,

3-D

iph

enyl

-4-c

arbo

eth

oxy

pyra

zole

-5-o

ne

525

3.5–

4.0

Aqu

eou

s0.

5–10

1.15

6C

u(I

I),C

o(II

),Z

n(I

I),

Mo(

VI)

,ED

TA[2

8]

Fe(I

I)D

yfor

myl

hydr

azin

e47

07.

3–9.

3A

queo

us

0.25

–13

0.32

58—

[29]

Fe(I

I)4,

7-D

iph

enyl

-1,1

0-ph

enan

thro

line

and

tetr

aph

enyl

bora

te53

4—

Ext

ract

ion

0–20

.02

—[3

0]

Fe(I

I)T

hio

cyan

ate-

acet

one

480

HC

lO4

Aqu

eou

s—

2.1

Cu

(II)

,N

O2− ,

S 2O

3−2

,H

2P

O4−2

,an

dC

2O

4−2

[31]

Fe(I

I)2-

Hyd

roxy

-1-n

aph

thal

dehy

de-p

-hyd

roxy

ben

zoic

hydr

azon

e40

55

Aqu

eou

s0.

05–1

.37

5.6

Sn(I

I),C

o(II

)N

i(II

)Z

n(I

I)A

l(II

I)C

u(I

I)P

rese

nt

met

hod

Co(

II)

Sodi

um

isoa

myl

xan

that

e40

04.

5–9.

0A

queo

us

3.0–

351.

92[1

6]C

o(II

)2-

Pyr

idin

eca

rbox

alde

hyde

ison

icot

inyl

-hyd

razi

ne

346

9A

queo

us

0.01

–2.7

7.1

Au

(III

),A

g(I)

,Pt(

III)

[18]

Co(

II)

2-H

ydro

xy-1

-nap

hth

alid

ene

salic

yloy

lhyd

razo

ne

430

8.0–

9.0

Ext

ract

ion

0–10

0.16

[22]

Co(

II)

Pyr

idin

e-2-

acet

alde

hyde

salic

yloy

lhyd

razo

ne

415

1.0–

6.0

Ext

ract

ion

0.5–

7.0

1.04

—[3

2]C

o(II

)B

is-4

-ph

enyl

-3-t

hio

sem

icar

bazo

ne

400

4—

0.6–

6.0

2.2

—[3

3]C

o(II

)2-

Hyd

roxy

-l-n

aph

thal

iden

e-sa

licyl

oylh

ydra

zon

e43

08.

0–9.

0E

xtra

ctio

n0–

101.

6×

103

—[2

2]C

o(II

)2-

(2-Q

uin

olyn

ylaz

o)-5

-dim

ethy

lam

ino

anili

ne

625

5.5

Ext

ract

ion

0.01

–0.6

4.3

Man

yca

tion

san

dan

ion

s[3

4]

Co(

II)

2-H

ydro

xy-3

-met

hox

ybe

nza

ldeh

yde

thio

sem

icar

bazo

ne

390

6A

queo

us

0.06

–2.3

52.

74—

[35]

Co(

II)

2-H

ydro

xy-1

-nap

hth

alde

hyde

-p-h

ydro

xybe

nzo

ichy

draz

one

425

5A

queo

us

0.12

–3.5

42.

3N

i(II

),Z

n(I

I),S

n(I

I),I

n(I

II),

and

Ga(

IIII

)P

rese

nt

met

hod


against the respective analyte concentrations. Fe(II) andCo(II) obeyed Beer’s law in the range 0.055–1.650 μg mL−1

and 0.117–4.719 μg mL−1 at 436 nm and 426 nm, respec-tively. Calibration plots were constructed for the standardsolutions containing Fe(II) alone and in the presence of0.589 μg mL−1 of Co(II). Similarly, the calibration graphswere constructed for standards containing Co(II) alone andin the presence of 0.330 μg mL−1 of Fe(II). The slopes, inter-cepts, and correlation coefficients of the prepared calibrationplots were calculated and given in Table 14. The derivativeamplitudes measured at 436 nm and 426 nm were found tobe independent of the concentration of Co(II) and Fe(II),respectively. This allows the determination of Fe(II) andCo(II) in their mixtures without any significant error andwithout the need for their prior separation.

3.5.3. Simultaneous Determination of Co(II) and Fe(II) inBinary Mixtures. Fe(II) and Co(II) were mixed in differentproportions and then treated with required amount ofHNAHBH in the presence of buffer solution (pH 5.5)and 0.15% of CTAB and diluted to the volume in 10 mLvolumetric flasks. The second-order derivative spectra forthese solutions were recorded (350–600 nm) and the deriva-tive amplitudes were measured at 436 nm and 426 nm.The amounts of Fe(II) and Co(II) in the mixtures takenwere calculated from the measured derivative amplitudesusing the respective predetermined calibration plots. Theresults obtained along with the recovery percentage andrelative errors are presented in Table 15, which indicate theusefulness of the proposed method for the simultaneousdetermination of Fe(II) and Co(II) in admixtures.

3.5.4. Simultaneous Determination of Iron and Cobalt inAlloy Samples. The developed second-order derivative spec-trophotometric method was employed for the simultaneousdetermination of iron and cobalt in some alloy samples.Appropriate volumes of the alloy samples were treated withrequired amount of HNAHBH at pH 5.5 in the presenceof 0.15% CTAB and diluted to 10 mL in standard flasks.The second-derivative curves for the resultant solutions wererecorded, and the derivative amplitudes were measured at426 nm and 436 nm. The amounts of iron and cobalt inthe samples were evaluated with the help of predeterminedcalibration plots and presented in Table 16.

4. Conclusions

A comparison of the analytical results of the proposedmethods was made with those of some of the recentlyreported spectrophotometric methods and presented inTable 17. The data in the above table reveals that theproposed method of determination of iron is more sensitivethan those reported by Malik and Rao [27], Patil and Dhuley[28], Nagabhushana et al. [29], Wang et al. [30], Zhang etal. [31], and Martins et al. [36]. The methods proposed byKatmal and Hoyakava [24], Morales and Toral [25], andReddy et al. [26] are more sensitive than the present method.However they are less selective than the proposed method as

they suffer interference from W(VI), Pd(II), Cr(III), Tl(I),Pb(II), Bi(III), Hg(II), Mo(VI), EDTA, CN−. Regarding thedetermination of cobalt, the present method is more sensitivethan those reported by Malik et al [16], Patil and Sawant [32],Adinarayana Reddy et al. [33], and Prabhulkar et al. [22].However, the preset method is less sensitive than the methodsreported by Guzor and Jin [21] and Qiufen et al. [34],but these methods are less selective due to the interferenceof many cations and anions. The results obtained in thesimultaneous determination of Fe(II) and Co(II) are wellcomparable with the reported methods. Above all mostof the reported methods involve extraction into spuriousorganic solvents where as the present methods are simple,nonextractive, and reasonably accurate.

References

[1] E. Wildermuth, H. Stark, G. Friedrich et al., “Iron com-pounds,” in Ullmann’s Encyclopedia of Industrial Chemistry,Wiley-VCH, 2000.

[2] F. C. Campbell, “Cobalt and cobalt alloys,” in Elementsof Metallurgy and Engineering Alloys, pp. 557–558, ASMInternational, 2008.

[3] M. L. C. Adolfsson, A. K. Saloranta, and M. K. Silander,“Colourant composition for paint products,” US Patent,Patent number: 5985987, 1999.

[4] M. W. Hentze and L. C. Kuhn, “Molecular control ofvertebrate iron metabolism: mRNA-based regulatory circuitsoperated by iron, nitric oxide, and oxidative stress,” Proceed-ings of the National Academy of Sciences of the United States ofAmerica, vol. 93, no. 16, pp. 8175–8182, 1996.

[5] R. Michel, M. Nolte, M. Reich, and F. Loer, “Systemic effectsof implanted prostheses made of cobalt-chromium alloys,”Archives of Orthopaedic and Trauma Surgery, vol. 110, no. 2,pp. 61–74, 1991.

[6] J. A. Disegi, R. L. Kennedy, and R. Pillia, Cobalt-Base Alloys forBiomedical Applications, ASTM International Standards, 1999.

[7] J. T. Ellis, I. Schulman, and C. H. Smith, “Generalized siderosiswith fibrosis of liver AND pancreas in cooley’s (Mediter-ranean) anemia with observations on the pathogenesis of thesiderosis AND fibrosis,” American Journal of Pathology, vol. 30,no. 2, pp. 287–309, 1954.

[8] Wu, Li-Xiang, Guo, and J. Cun, Metallurgical Analysis, vol. 24,no. 3, pp. 66–68, 2004.

[9] L. Zaijun, F. You, L. Zhongyun, and T. Jian, “Spectropho-tometric determination of iron(III)-dimethyldithiocarbamate(ferbam) using 9-(4-carboxyphenyl)-2,3,7-trihydroxyl-6-fluorone,” Talanta, vol. 63, no. 3, pp. 647–651, 2004.

[10] Qi-Kai Zhang, Ling-Zhao Kong, and Li Wang, “Spectropho-tometric determination of micro amount of iron in oils withthiocyanate-phenanthroline-OP,” Fenxi Shiyanshi (AnalyticalLaboratory), vol. 24, no. 1, pp. 77–79, 2005.

[11] P. K. Tarafder and R. Thakur, “Surfactant-mediated extractionof iron and its spectrophotometric determination in rocks,minerals, soils, stream sediments and water samples,” Micro-chemical Journal, vol. 80, no. 1, pp. 39–43, 2005.

[12] F. G. Martins, J. F. Andrade, A. C. Pimenta, L. M. Lourenco,J. R. M. Casto, and V. R. Balbo, “Spectrophotometric study ofiron oxidation in the iron(II)/thiocyanate/acetone system andsome analytical applications,” Ecletica Quımica, vol. 30, no. 3,pp. 63–71, 2005.


[13] A. K. Sharma and I. Singh, “Spectrophotometric trace deter-mination of iron in food, milk, and tea samples using a newbis-azo dye as analytical reagent,” Food Analytical Methods, vol.2, no. 3, pp. 221–225, 2009.

[14] L. I. Cheng-hong, G. E. Chang-hua, L. Hua-ding, and P. Fu-you, “Spectrophotometric determination of iron with 2-(5-carboxy-1,3,4-triazolylazo)-5-diethylamino aniline ,” ScienceTechnology and Engineering, vol. 21, pp. 5780–5782, 2008.

[15] Q. Z. Zhai, “Catalytic kinetic spectrophotometric determina-tion of trace copper with copper(II)-p-acetylchloro-phosphonazo-hydrogen peroxide system,” Bulletin of theChemical Society of Ethiopia, vol. 23, no. 3, pp. 327–335, 2009.

[16] A. K. Malik, K. N. Kaul, B. S. Lark, W. Faubel, and A.L. J. Rao, “Spectrophotometric determination of cobalt,nickel palladium, copper, ruthenium and molybdenum usingsodium isoamylxanthate in presence of surfactants,” TurkishJournal of Chemistry, vol. 25, no. 1, pp. 99–105, 2001.

[17] B. R. Reddy, P. Radhika, J. R. Kumar, D. N. Priya, andK. Rajgopal, “Extractive spectrophotometric determinationof cobalt(II) in synthetic and pharmaceutical samples usingcyanex 923,” Analytical Sciences, vol. 20, no. 2, pp. 345–349,2004.

[18] G. A. Shar and G. A. Soomro, “Spectrophotometric deter-mination of cobalt(II), nickel(II) and copper (II) with 1-(2pyridylazo)-2-naphthol in micellar medium,” The Nucleus,vol. 41, pp. 77–82, 2004.

[19] N. Veerachalee, P. Taweema, and A. Songsasen, “Complexationand spectrophotometric determination of cobalt(II) ion with3-(2′-thiazolylazo)-2,6-diaminopyridine,” Kasetsart Journal—Natural Science, vol. 41, no. 4, pp. 675–680, 2007.

[20] Y. Haoyi, Z. Guoxiu, and Y. Gaohua, “Determination of cobaltin terephthalic acid by picramazochrom spectrophotometry,”Chemical Analysis and Meterage, vol. 1, 2009.

[21] S. H. Guzar and Q. H. Jin, “Simple, selective, and sensi-tive spectrophotometric method for determination of traceamounts of nickel(II), copper (II), cobalt (II), and iron (III)with a novel reagent 2-pyridine carboxaldehyde isonicotinylhydrazone,” Chemical Research in Chinese Universities, vol. 24,no. 2, pp. 143–147, 2008.

[22] S. G. Prabhulkar and R. M. Patil, “2-Hydroxy-1-naphthalidinesalicylohydrazone as an analytical reagent for extractive spec-trophotometric determination of a biologically and indus-trially important metal Cobalt(II),” International Journal ofChemical Sciences, vol. 6, no. 3, pp. 1480–1485, 2008.

[23] J. E. Huheey, E. A. Keiter, and R. L. Keiter, Inorganic Chemistry,Harper Collins, New York, NY, USA, 4th edition, 1993.

[24] T. Katami, T. Hayakawa, M. Furukawa, and S. Shibata,“Extraction—spectrophotometric determination of iron with2-[2-(3,5-Dibromopyridyl)azo]-5-dimethylaminobenzoicacid,” The Analyst, vol. 109, no. 2, pp. 159–162, 1984.

[25] A. Morales and M. I. Toral, “Extraction—spectrophotometricdetermination of iron as the ternary tris(1,10-phenan-throline)-iron(II)-picrate complex,” The Analyst, vol. 110, no.12, pp. 1445–1449, 1985.

[26] M. R. P. Reddy, P. V. S. Kumar, J. P. Shyamsundar, and J.S. Anjaneyulu, “Extractive spectrophotometric method forthe determination of iron in titanium base alloys using4-(2-Pyridylazo) resorcinol and a long chain quaternaryammonium salt,” Journal of the Indian Chemical Society, vol.66, pp. 437–439, 1989.

[27] A. K. Malik and A. L. J. Rao, “Spectrophotometric determina-tion of iron(III) dimethyldithiocarbamate (ferbam),” Talanta,vol. 44, no. 2, pp. 177–183, 1997.

[28] R. K. Patil and D. G. Dhuley, “Solvent extraction and spec-trophotometric determination of Fe(II) with 1,3-diphenyl-4-carboethoxy pyrazole-5-one,” Indian Journal of Chemistry, vol.39, no. 10, pp. 1105–1106, 2000.

[29] B. M. Nagabhushana, G. T. Chandrappa, B. Nagappa, andN. H. Nagaraj, “Diformylhydrazine as analytical reagent forspectrophotometric determination of iron(II) and iron(III),”Analytical and Bioanalytical Chemistry, vol. 373, no. 4-5, pp.299–303, 2002.

[30] L. M. Wang, C. Song, and J. Jin, “Spectrophotometric deter-mination of iron by extraction of its ternary complex with4,7-diphenyl-1,10-phenanthroline and tetraphenylborate intomolten naphthalene,” Fenxi Shiyanshi (Analytical Laboratory),vol. 23, no. 9, pp. 48–50, 2004.

[31] F. G. Martins, J. F. Andrade, A. C. Pimenta, L. M. Lourenco,J. R. M. Casto, and V. R. Balbo, “Spectrophotometric study ofiron oxidation in the iron(II) thiocyanateacetone system andsome analytical application,” Electica Quimica, vol. 30, no. 3,pp. 63–71, 2005.

[32] S. S. Patil and A. D. Sawant, “Pyridine-2-acetaldehyde salicy-loylhydrazone as reagent for extractive and spectrophotomet-ric determination of cobalt(II) at trace level,” Indian Journal ofChemical Technology, vol. 8, no. 2, pp. 88–91, 2001.

[33] S. Adinarayana Reddy, K. Janardhan Reddy, S. LakshmiNarayana, Y. Sarala, and A. Varada Reddy, “Synthesis ofnew reagent 2,6-diacetylpyridine bis-4-phenyl-3- thiosemicar-bazone (2,6-DAPBPTSC): Selective, sensitive and extractivespectrophotometric determination of Co(II) in vegetable, soil,pharmaceutical and alloy samples,” Journal of the ChineseChemical Society, vol. 55, no. 2, pp. 326–334, 2008.

[34] Q. Qiufen, G. Yang, X. Dong, and J. Yin, “Study on the solidphase extraction and spectrophotometric determination ofcobalt with 2-(2-quinolylazo)-5-diethylaminoaniline,” TurkishJournal of Chemistry, vol. 28, no. 5, pp. 611–619, 2004.

[35] A. P. Kumar, P. R. Reddy, and V. K. Reddy, “Direct andderivative spectrophotometric determination of cobalt (II) inmicrogram quantities with 2-hydroxy-3-methoxy benzalde-hyde thiosemicarbazone,” Journal of the Korean ChemicalSociety, vol. 51, no. 4, pp. 331–338, 2007.

[36] F. G. Martins, J. F. Andrade, A. C. Pimenta, L. M. Lourenco, J.R. M. Castro, and V. R. Balbo, “Spectrophotometric study ofiron oxidation in the iron(II)/thiocyanate/ acetone system andsome analytical applications,” Ecletica Quimica, vol. 30, no. 3,pp. 63–71, 2005.

Submit your manuscripts athttp://www.hindawi.com

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation http://www.hindawi.com Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation http://www.hindawi.com Volume 2014


CatalystsJournal of

SpectrophotometricDeterminationofIron(II)andCobalt(II)by...

Documents

Transcript of SpectrophotometricDeterminationofIron(II)andCobalt(II)by...